An automated line for producing workpieces generally comprises a succession of work stations each having operational units connected to a controller. There exist very numerous types of operational unit, and for example: handling robots; welding robots; automatic machine tools; position-holding tools; conveyors; movable positioning means; and clamping members, . . . . In each work station, the operational units are arranged and controlled so as to act together on one or more workpieces by the operational units performing sequences of actions. The controller executes a control program that coordinates and synchronizes the operational units and triggers the actions to be performed by each operational unit. Actions may be performed in succession or simultaneously by a plurality of operational units, with the operational units then acting simultaneously and independently, until their respective actions have come to an end.
The control program is designed specially for each work station as a function of the requirements of the user of the work station. Program design includes a step of writing the program in a high level language or user language, and a step of compiling the program in which the high level language program is translated into machine language. Program preparation, and in particular program compilation are relatively lengthy and require significant computer resources. In this mode of operation, the program needs to be rewritten in full or in part for each new work station or for any modification to an existing work station. However, such a control program is relatively complex, particularly when the number of robots is large, so that coordinating and synchronizing movements, functions, and actions of the robots becomes difficult, such that rewriting all or part of the program requires highly skilled personnel. Taking action on the program is thus relatively lengthy and expensive, which is penalizing when it is necessary to comply with flexibility requirements.